Polyetherimide ester polymers comprised of the reaction products of (a) a diol, (b) a dicarboxylic acid, (c) a high molecular weight poly(oxy alkylene) diamine, and (d) a tricarboxylic acid or its derivative are known and are described in U.S. Pat. Nos. 4,544,734 and 4,556,705 to McCready and in U.S. Pat. No. 4,556,688 to McCready et al. These polyetherimide esters exhibit excellent stress-strain properties, low tensile set, high melting temperatures and/or excellent strength/toughness characteristics as well as superior flexibility, which properties render them especially suitable for molding and extrusion applications.
It has now been discovered that polyetherimide esters exhibiting useful properties can be provided by utilizing a diamine reactant which is comprised of a mixture of a high molecular weight poly(oxy alkylene) diamine and a relatively low molecular weight aromatic or aliphatic diamine.